We have established that Rhesus monkeys are able to control with accuracy their daily caloric intake by reducing their feeding after preloads of intragastric nutrients calorie for calorie. We propose a series of experiments to study this control in relation to the altered endocrine and metabolic states produced by ventromedial and lateral hypothalamic lesions. These animals will be compared with normal animals following over-feeding and fasting. We plan to correlate feeding changes with the body weight and metabolic deviations. We propose to analyze the mechanisms by which the particular energy ingestion is self regulated by the animals in these various conditions. As we have shown that this caloric regulation can be effected while preload remains in the stomach, we plan to analyze the mechanisms by which the stomach, small intestine and vagus nerve could possibly mediate this control. The objectives then are to document the correlation between feeding control and endocrine and metabolic state and to analyze the gastrointestinal and neuronal mechanisms responsible for it.